Declining an online reservation is easy:

Step 1: Click on a reservation.

Step 2: Select "Decline" at the top of the page.

Step 3: Customize your "Declination Message" (optional)

Step 4: Click "Decline" at the bottom of the page.
​Step 5: Done

Step 1: Go to your "Today" screen.

Step 2: Tap on the reservation.

Step 3: Select "Decline"

Step 4: Customize Your Email Response (optional)
​Step 5: Tap "Decline" at the top of the page.